Start by washing and chopping the rhubarb into small pieces.

Place the chopped rhubarb in a large pot with water and cook over medium heat, stirring occasionally, until mushy, about 10-15 minutes.

Remove from heat and strain the mixture using a fine mesh strainer, pressing down to extract as much juice as possible.

Measure out 4 cups of the strained rhubarb juice.

In a clean pot, combine the rhubarb juice, lemon juice, and pectin; stir well to dissolve the pectin.

Bring the mixture to a rolling boil over high heat, stirring constantly.

Once boiling, quickly stir in the sugar all at once, return to a boil, and cook for 1-2 minutes until sugar is fully dissolved.

Remove from heat, skim off any foam if necessary, and pour the hot jelly into sterilized canning jars using a funnel.

Process your jars in a water bath for at least 10 minutes to ensure proper sealing.